1. Field of the Invention
This invention relates to electronic circuit technology, and more particularly, to a control device for fast transient recovery of the output of a DC (direct current) power output device, such as DC-DC converters.
2. Description of Related Art
DC-DC converters are an electronic circuit component that is nowadays widely used in many types of computers and intelligent electronic devices for providing DC power. In operation, a DC-DC converter is capable of converting an input DC voltage having a higher amplitude (such as battery-supplied voltage) to an output DC voltage having a lower amplitude, such that the down-converted DC voltage is used to drive low-voltage IC (integrated circuit) chips, such as microprocessors, memory modules, digital signal processing chips, to name just a few. Nowadays, the present IC technology allows IC chips to operate with a system voltage as low as 0.8 V with a current of 200 A.
In practical applications, however, the operation of modern IC chips may provide serious load current variation in range of 20 A to 200 A due to the complexity thereof. Such serious load current variation may cause much serious output voltage transient response, such as over-shoot and under-shoot, to make the output voltage substantially deviating from the steady state value, which the output voltage should achieve. The output voltage may be provided with larger difference between the steady state value and the transient response by this deviation, thereby slowing down the transient response recovery. One solution to this problem is to employ large decoupling capacitors for reducing transient ripples, and the smaller transient ripples allow the output voltage of DC-DC converters to return to steady state more quickly. In practice, however, the solution with the large capacitors has two drawbacks: firstly, it is costly in price to purchase and thus would increase the overall manufacture cost of DC-DC converters; and secondly, due to the bulky size of the large capacitors, it would require a large circuit layout area for implementation of the DC-DC converters.
In view of the aforementioned problem, there exists a need and a research effort in the electronic industry for a new circuit technology that may allow the fast transient recovery of the output voltage of DC-DC converters.